The present invention relates to a heat resistant scattering-preventing composite material which is produced by applying, to a substrate, a fluorine-containing polymer excellent in heat resistance, non-sticking property, transparency (property for exhibiting clear surface pattern), stain-proofing property, water and oil repellency and particularly adhesive property to the substrate. Further the present invention particularly relates to a heat resistant scattering-preventing composite material which is suitably used, by utilizing its characteristic of heat resistance, for products scattering when broken, for example, illumination apparatuses such as electric bulbs, displaying apparatuses such as CRT and liquid crystal display, building materials such as window glass, cooking wares such as glass containers, and the like.
An electric bulb and a lamp shade are made of mainly glass or polycarbonate from the viewpoint of heat resistance, elasticity, and further light transmittancy (transparency). However there is a danger that those materials are easily broken and broken pieces are scattered.
Prevention of scattering of the broken pieces are tried by laminating with a film of synthetic resin such as polyvinyl butyral, applying a silicon resin coating or enclosing an electric bulb and a vicinity thereof with a net.
However since an electric bulb becomes high in temperature (from about 50xc2x0 to about 150xc2x0 C.) while it is turned on, in a method of laminating a conventional film, heat resistance of the film is insufficient (A temperature for continuous use is low) and deterioration of the laminated film such as softening, foaming, lowering of strength and coloring occurs. Thus functions thereof cannot be exhibited fully during long-term use required basically. In case of a silicon resin, staining easily occurs, transparency is lowered and a problem with light transmittancy occurs even when a metal net is used.
A laminated glass or wired glass of polyvinyl butyral is used on glass for cars, glass for green house exposed directly to sun light and explosion-proof glass for building in addition to glass for illumination. Particularly for application to building, those materials are insufficient in view of light weight and non-flammability required.
On the contrary, a fluorine-containing resin is excellent particularly in heat resistance, stain-proofing property, non-sticking property, chemical resistance and weather resistance, and is said to be a suitable material when being in the form of film or coating composition.
However the fluorine-containing resin has an essential problem that due to its non-sticking property, its adhesion to a substrate of glass or synthetic resin is not sufficient.
When adhering a fluorine-containing resin coating composition to a glass substrate, etc. requiring transparency, an improvement of adhesion has been tried by treating a substrate surface with a silane coupling agent or adding a silicone resin to a fluorine-containing resin coating composition (JP-B-54-42366, JP-A-5-177768, etc.). However enhancement of adhesion is insufficient, heat resistance is lowered, and separation of film, foaming and coloring easily arise at sintering or during use at high temperature.
Particularly JP-B-3-80741 discloses an electric bulb coated with a fluorine-containing resin powder coating composition, in which roughening of a glass substrate to be adhered, coating of a primer such as silane coupling agent and coating of a fluorine-containing resin powder coating composition containing glass fiber are carried out. However there are problems with complicated steps, lowering of light transmittancy by roughening and due to glass fiber, and coloring of a primer. The fluorine-containing resin is inherently insufficient in adhesion.
On the contrary, fluorine-containing resin coating compositions prepared by copolymerizing a hydrocarbon monomer (containing no fluorine) containing functional group such as hydroxyl or carboxyl have been discussed. However since those coating compositions were originally studied mainly for a purpose of weather resistance, it is difficult to use them for application requiring heat resistance (for example, 200xc2x0 to 350xc2x0 C.) which is directed by the present invention.
Namely with respect to a polymer prepared by copolymerizing a hydrocarbon monomer (containing no fluorine) having functional group, thermal decomposition easily occurs on components of the monomer at the time of processing at high temperature or during use, and thus coating film failure, coloring, foaming, separation, etc. arise, which lowers heat resistance and property for preventing scattering and makes it impossible to attain purposes of coating a fluorine-containing resin.
Further fluorine-containing polymers are generally insufficient in mechanical strength and dimensional stability, and high in price. In order to minimize those disadvantages and make the best use of the above-mentioned merits which the fluorine-containing polymer possesses inherently, investigations have been made also with respect to its use in the form of film.
However the fluorine-containing polymer inherently has low adhesive force as mentioned above, and it is difficult to adhere the fluorine-containing polymer directly to other material (substrate). For example, even if the adhering is tried by thermo-processing, adhesive strength of the fluorine-containing polymer is not enough, or even if the polymer has adhesive force to a certain extent, such an adhesive force is apt to vary depending on kind of the substrate. Thus in many cases, reliability on the adhesive strength of the fluorine-containing polymer has been not so enough.
In order to adhere the fluorine-containing polymer film to a substrate, mainly the following methods have been studied:
1. a method for physically roughening a surface of substrate by sand blasting, etc.,
2. a method for surface-treating a fluorine-containing resin film by chemical treatment such as sodium etching, plasma treatment, photochemical treatment, etc.,
3. a method for adhering by using an adhesive, and other methods.
With respect to the methods 1 and 2 above, surface-treating steps are required, and the steps are complicated and productivity is poor. Also kinds and shapes of substrates are restricted. Further the obtained adhesive force is insufficient, and heat resistance which the fluorine-containing resin inherently possesses is easily lowered. Also the method of using a chemical such as sodium etching has a problem with safety.
Use of an adhesive in the method 3 above has also been discussed. A usual hydrocarbon type (non-fluorine-containing) adhesive does not have enough adhesive property and its heat resistance is insufficient. Thus a hydrocarbon type adhesive cannot stand under conditions for adhering of a fluorine-containing polymer film which requires molding and processing at high temperature, and peeling due to decomposition of the adhesive and coloring occur. Since the above-mentioned composite material produced by using an adhesive also is insufficient in heat resistance, chemical resistance and water resistance of its adhesive layer, it cannot maintain adhesive force due to a change in temperature and environment, and lacks in reliability.
On the contrary, adhesion by using an adhesive composition comprising a fluorine-containing polymer having functional group is discussed.
For example, it is reported that a fluorine-containing polymer prepared by graft-polymerizing, to the fluorine-containing polymer, a hydrocarbon monomer which has carboxyl represented by maleic anhydride and vinyltrimethoxysilane, a residual group of carbonic acid, epoxy or a hydrolyzable silyl group, is used as an adhesive (for example, JP-A-7-18035, JP-A-7-25952, JP-A-7-25954, JP-A-7-173230, JP-A-7-173446, JP-A-7-173447) and that an adhesive composition comprising a fluorine-containing copolymer prepared by copolymerizing a hydrocarbon monomer having functional group such as hydroxyalkyl vinyl ether with tetrafluoroethylene or chlorotrifluoroethylene and an isocyanate hardening agent is cured and used as an adhesive between vinyl chloride resin and corona-discharged ETFE (for example, JP-A-7-228848).
The above-mentioned adhesive composition comprising a fluorine-containing resin prepared by graft-polymerizing or copolymerizing a hydrocarbon monomer having functional group does not have enough heat resistance, and thus at the time of processing a composite material comprising the adhesive composition and a fluorine-containing resin film at high temperature or during use at high temperature, decomposition and foaming occur, thereby causing reduction of adhesive strength, peeling and coloration. In case of the adhesive composition disclosed in JP-A-7-228848, it is necessary to corona-discharge the fluorine-containing resin film.
As mentioned above, there have been no material for heat resistant scattering-preventing composite material which assures strong adhesion to a substrate while maintaining transparency.
In view of the above-mentioned facts, an object of the present invention is to provide a heat resistant scattering-preventing composite material which is produced by applying, to a substrate, a material comprising a fluorine-containing polymer being excellent in adhesion to the substrate without necessitating complicated steps.
Further the heat resistant scattering-preventing composite material of the present invention is excellent in transparency (property for exhibiting clear surface pattern), non-sticking property, stain-proofing property, chemical resistance, weather resistance, water and oil repellency, stain removing property, rust preventing property and antibacterial property.
The present invention relates to a heat resistant scattering-preventing composite material which is produced by applying, to a substrate, a material comprising a fluorine-containing ethylenic polymer having functional group and prepared by copolymerizing:
(a) 0.05 to 30% by mole of at least one of fluorine-containing ethylenic monomers having at least one functional group selected from the group consisting of hydroxyl, carboxyl, a carboxylic salt group, a carboxylic ester group and epoxy and
(b) 70 to 99.95% by mole of at least one of fluorine-containing ethylenic monomers having no functional group mentioned above.
In that case, it is preferable that the above-mentioned fluorine-containing ethylenic monomer (a) having functional group is at least one of fluorine-containing ethylenic monomers represented by the formula (1):
CX2xe2x95x90CX1xe2x80x94Rfxe2x80x94Yxe2x80x83xe2x80x83(1)
wherein Y is xe2x80x94CH2OH, xe2x80x94COOH, a carboxylic salt group, a carboxylic ester group or epoxy, X and X1 are the same or different and each is hydrogen atom or fluorine atom, Rf is a divalent fluorine-containing alkylene group having 1 to 40 carbon atoms, a fluorine-containing oxyalkylene group having 1 to 40 carbon atoms, a fluorine-containing alkylene group having ether bond and 1 to 40 carbon atoms or a fluorine-containing oxyalkylene group having ether bond and 1 to 40 carbon atoms.
Further it is preferable that the fluorine-containing ethylenic monomer (b) having no functional group mentioned above is tetrafluoroethylene.
Further it is preferable that the fluorine-containing ethylenic monomer (b) having no functional group mentioned above is a monomer mixture comprising 85 to 99.7% by mole of tetrafluoroethylene and 0.3 to 15% by mole of a monomer represented by the formula (2):
CF2xe2x95x90CFxe2x80x94Rf1xe2x80x83xe2x80x83(2)
wherein Rf1 is CF3 or ORf2, in which Rf2 is a perfluoroalkyl group having 1 to 5 carbon atoms.
Further it is preferable that the fluorine-containing ethylenic monomer (b) having no functional group mentioned above is a monomer mixture comprising 40 to 80% by mole of tetrafluoroethylene, 20 to 60% by mole of ethylene and 0 to 15% by mole of other monomer copolymerizable with those monomers.
In the present invention, it is preferable that the fluorine-containing ethylenic polymer having functional group is applied to a substrate in the form of a coating, aqueous dispersion, powder coating or film.
Further the substrate may be a ceramic such as glass and a synthetic resin.
The heat resistant scattering-preventing composite material of the present invention can be suitably used for appliances and parts becoming high in temperature and being easily broken, for example, electric bulbs and further for fire-protection safety glass requiring non-flammability and fire resistance.